In full-bleed spreads saturated with twilight colors, Morales (Los Gatos Black on Halloween ) follows Mother Sky as she prepares her tiny daughter, Little Night, for the evening. Mother Sky, whose black braids hang down her back and whose ample peasant dress flows with sunset pink and vermilion, empties stars into a tub for Little Night's bath, readies a dress crocheted from clouds and tries to find her daughter, who, like all children, would rather hide from Mama than mind her. ""Mother Sky hovers by the shade of trees. She searches in the stripes of bees. When she peeks inside the bats' cave, whom does she see?"" After a snack of starry milk and more hide-and-seek, it's time to comb Little Night's hair, which her mother fastens with barrettes named for the planets (""Venus on the east, Mercury on the west, and Jupiter above""). By now, Mother Sky's dress has darkened, and the planets gleam in Little Night's black hair. But, despite what young readers may have suspected, the young heroine does not go to bed. ""Now, my Little Night, take your moon ball and play!"" Little Night skips past Mother Sky, the glowing lights of city buildings beneath her feet, the moon leaping from her hands. Creating what amounts to a new myth may seem an ambitious project, but Morales succeeds by combining intimacy and grandeur. Children will love the idea of a girl who plays while most sleep. Ages 4-8.(Apr.)